A Survey of Biochars: Interactions with Dissolved Ammonia, Nitrate, and Phosphate

Edward Colosky - Graduate Student at the University of Minnesota in St. Paul, MN. Prior published field- and lab-based studies show that biochar soil amendments can reduce nitrogen (N) and phosphorous (P) leached from soil, suggesting a biochar-nutrient interaction. Although studies have examined individual biochars N and P interactions, no study has systematically surveyed biochars from various production processes and different parent materials. This study examined the ammonium (NH4), nitrate (NO3), and phosphate (PO4) sorption potentials of over 30 different biochars using a simple 24 hr batch sorption experiment. The observed sorption coefficients vary for each biochar. There does not appear to be a clear feedstock dependency, but manure-based biochars exhibit leachable P. There are biochars that absorb all three nutrients, but the most common occurrence among biochars is that more phosphate is given off than absorbed. These results stress the need for an individual biochar to be screened to ensure that it possesses the desired property before field application.Ope